Engine mount structure for vehicle

ABSTRACT

An engine mount mounts a motive power source to a vehicle body. The engine mount includes an inner cylindrical member attached to the motive power source, and a resinous bracket attached to the vehicle body. The inner cylindrical member is elastically connected to the bracket. The bracket includes a cold shut portion and a weak portion provided at the cold shut portion. The cold shut portion is formed when the bracket is molded from molten resin. The weak portion has such a small strength that, when the vehicle body collides with some object, the bracket is fractured to absorb the collision.

TECHNICAL FIELD

The present invention relates to a vehicular engine mount designed tohave a fracture strength set such that the engine mount is fracturedduring collision of a vehicle.

BACKGROUND ART

Known engine mounts are structured to have resinous members mounted tobodies of vehicles. One example of such engine mounts is disclosed inJapanese Patent Laid-Open Publication No. HEI 6-173988.

FIG. 6 hereof shows an anti-vibration member disclosed in thepublication. The anti-vibration member includes a plastic bracketportion 101 mounted to a vehicle body, a rubber 102 connected to thebracket portion 101, and an inner cylindrical member 103 connected tothe rubber 102 and mounted to an engine. The anti-vibration member alsoincludes an inertial member 104.

Vehicles should have not only their front parts of sufficient rigiditybut also engines, deemed to be a rigid body, displaceable by acontrolled distance during head-on collision or offset collision of thevehicles for the purpose of protecting passengers within the vehicles.

During the collision, the front part of the vehicle is subjected to agreat force. If the engine is then easily movable rearwardly, it ispossible to absorb the collision.

The vehicle has the engine mounted to a vehicle body thereof throughengine mounts. The engine mount is required to fracture or operate in astroke sufficient to displace the engine by a greater distance duringcollision of the vehicle.

However, the anti-vibration member disclosed in the publication is notarranged to break or operate in a stroke necessary to displace theengine by the greater distance. Moreover, the anti-vibration member doesnot have its fracture strength set allowing for the displacement of theengine during the collision of the vehicle.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a vehicular enginemount improved to provide a fracture strength set such that the enginemount is broken by undergoing a force developed during collision of avehicle.

According to a first aspect of the present invention, there is providedan engine mount for mounting to a vehicle body a motive power sourceincluding an engine and a transmission, comprising: an inner cylindricalmember to be mounted to one of the motive power source and the vehiclebody; an outer mounting member to be mounted to the other of the motivepower source and the vehicle body, the outer mounting member beingelastically connected to the inner cylindrical member; and the outermounting member having a cylindrical portion loosely receiving the innercylindrical member therein such that the inner cylindrical member ismovable in both axial and radial directions thereof relative to thecylindrical portion, the outer mounting member having a weak portion forfracturing the outer mounting member to displace the motive power sourcerearwardly of the vehicle body during collision of the vehicle body, theweak portion being provided at a cold shut portion, formed when theouter mounting member is molded from molten resin, of the outer mountingmember.

In a preferred form of the present invention, the molding of the outermounting member is performed through the use of a mold having a cavityformed therein and a columnar part disposed within the cavity to providethe cylindrical portion during the molding of the outer mounting member,the columnar part being capable of dividing the molten resin into twoparts during the molding of the outer mounting member, such that the twoparts of the molten resin flow within the cavity to surround thecolumnar part and join together to provide the cold shut portion.

According to a second aspect of the present invention, there is providedan engine mount for mounting to a vehicle body a motive power sourceincluding an engine and a transmission, comprising: an inner cylindricalmember to be mounted to one of the motive power source and the vehiclebody; a resinous outer mounting member to be mounted to the other of themotive power source and the vehicle body; an elastic member connectingthe inner cylindrical member to the outer mounting member; the outermounting member having a cylindrical portion surrounding the innercylindrical member with a predetermined interval provided therebetween;and the outer mounting member having a cold shut portion and a weakportion provided at the cold shut portion, the cold shut portion beingformed when the outer mounting member is molded from molten resinthrough the use of a mold having a cavity formed therein and a columnarpart disposed within the cavity to provide the cylindrical portionduring the molding of the outer mounting member, the columnar part beingcapable of dividing the molten resin into two parts during the moldingof the outer mounting member, such that the two parts of the moltenresin flow within the cavity to surround the columnar part and jointogether to provide the cold shut portion.

The weak portion is sized and arranged to cooperate with the cold shutportion of small strength so as to provide the engine mount withfracture strength set such that: (1) when the vehicle is in such normaloperation as acceleration, deceleration, skidding and traveling on arough terrain, to thereby vibrate the motive power source, the enginemount absorbs the vibration transmitted to the motive power sourcewithout the resinous bracket being broken; and (2) when the vehiclecollides with some object to thereby exert a force on the motive powersource, the engine mount absorbs the collision by breaking the resinousbracket.

BRIEF DESCRIPTION OF DRAWINGS

A certain preferred embodiment of the present invention will hereinafterbe described in detail, by way of example only, with reference to theaccompanying drawings, in which:

FIG. 1 is a top plan view of an engine compartment of a vehicle havingan engine mount of the present invention disposed therein;

FIG. 2 is a top plan view of the engine mount mounted at its side wallto a left front side frame of the vehicle;

FIG. 3 is a side elevation view of the engine mount;

FIG. 4A through FIG. 4D illustrate how the engine mount is molded out ofmolten resin flowing within a cavity of a mold in accordance with thepresent invention;

FIG. 5A shows the engine mount undergoing a force produced when thevehicle is in normal operation and FIG. 5B shows the engine mountundergoing a force produced by collision of the vehicle; and

FIG. 6 illustrates partly in cross-section a conventional engine mount.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, there are shown vehicular components disposedwithin an engine compartment of a vehicle. It is to be noted that anarrow labeled “front” points in a forward direction of the vehicle.

The vehicular components include an engine 10, a transmission 11connected to one side of the engine 10, a subframe 12 and right and leftfront side frames (only left one shown and designated at 15). Thesubframe 12 and the front side frames support the engine 10 and thetransmission 11. The engine 10 and the transmission 11 cooperate witheach other to constitute a motive power source 13.

The subframe 12 is an assembly mounted to the right and left front sideframes. The subframe 12 includes right and left subframe portions 22, 21and front and rear beams 23, 24. The subframe portions 22, 21 extend ina front-and-rear direction of the vehicle. The front beam 23 extendsbetween front parts of the subframe portions 22, 21 while the rear beam24 extends between rear parts of the subframe portions 22, 21. At aportion where the right subframe portion 22 is joined to the front beam23, there is mounted a right plate 27. At a portion where the leftsubframe portion 21 is joined to the front beam 23, there is mounted aleft plate 26.

The engine 10 and the transmission 11 are supported by front and rearmounts 31, 32, an engine side mount 33, a transmission upper mount 34and transmission lower mounts 36, 37. The front mount 31 is positionedat a substantially central portion of a front part of the motive powersource 13 or engine 10. The rear mount 32 is positioned between andbehind rear parts of the engine 10 and the transmission 11. The engineside mount 33 is positioned on the other side of the engine 10positioned opposite the one side joined to the transmission 11. Thetransmission upper mount 34 is positioned on one side of thetransmission 11. More specifically, the transmission upper mount 34 isdisposed on a side edge of the transmission 11. The transmission lowermounts 36, 37 are positioned beneath the one side of the transmission11.

Such a transmission upper mount 34 is an engine mount of the presentinvention. The transmission upper mount 34 is attached to thetransmission 11 through a mount bracket 39. The transmission upper mount34 is attached directly to the left front side frame 15 provided on avehicle body of the vehicle. The term “engine mount” as used hereinmeans a member for elastically holding or mounting the motive powersource 13 to the vehicle body.

The engine 10 includes an intake manifold 41, and an exhaust manifoldhaving an exhaust pipe 42 mounted thereto. The right and left subframeportions 22, 21 have a stabilizer 45 extending transversely thereof. Thestabilizer 45 is mounted to the rear parts of the subframe portions 22,21 by means of brackets 46, 46. Reference numeral 47 denotes asuspension arm.

As shown in FIG. 2, the front side frame 15 has nuts 52, 52, 52 weldedthereto. The transmission upper mount 34 is attached to an inner surfaceof the front side frame 15 with bolts 51 threadedly engaged with thenuts.

The transmission upper mount 34 includes a resinous bracket 54 mountedto the front side frame 15, a metal inner cylindrical member 55 mountedto the mount bracket 39 mounted to the transmission 11, and an elasticmember 56 connecting the resinous bracket 54 to the inner cylindricalmember 55. The elastic member 56 is a rubber, for example. In otherwords, the resinous bracket 54 is elastically connected to the innercylindrical member 55.

The resinous bracket 54 includes a tubular or cylindrical portion 57.The cylindrical portion 57 has its inner peripheral surface 57 adefining an opening or space 58 of cylindrical configuration. Thecylindrical portion 57 surrounds the inner cylindrical member 55. Theinner cylindrical member 55 has its outer peripheral surface 55 a spacedfrom the inner peripheral surface 57 a by a predetermined interval ordistance d. In other words, the inner cylindrical member 55 is looselyreceived in the cylindrical portion 57. With this arrangement, the innercylindrical member 55 is movable radially and axially thereof relativeto the cylindrical portion 57. More specifically, the inner cylindricalmember 55 and the elastic member 56 are positioned in the space 58. Thebracket 54 has a cold shut portion 61 formed when the bracket 54 ismolded out of molten resin, as will be described later. The bracket 54includes a weak or fragile portion 63 having a hole 62 formed to extendvertically through the cold shut portion 61. The hole 62 extendshorizontally in the form of an arc. More specifically, as viewed in topplan, the hole 62 takes the form of an arc extending transversely of andsubstantially perpendicularly to the cold shut portion 61. The cold shutportion 61 is positioned or formed in parallel to a direction ofexertion of force on the transmission upper mount 34 during collision ofthe vehicle with some object, as will be discussed later in relation toFIG. 5A and FIG. 5B. As will be described later with reference to FIG.4A through FIG. 4D, during molding of the bracket 54, two flows or partsof melted resin come together to produce such a cold shut portion 61.The elastic member 56 is mounted within the space 58 in contact with theinner peripheral surface 57 a of the cylindrical portion 57. The coldshut portion 61 is formed in texture of the resinous bracket 54. Thecold shut portion 61 of the bracket 54 has its opposite sides 54 a, 54 bhaving smaller strength than the rest of the resinous bracket 54. Inaccordance with the present invention, the cold shut portion 61 ispositively or advantageously used to facilitate breaking the bracket 54when the vehicle body collides with some object. No one has found thatsuch a cold shut portion 61 of small strength is formed for the purposeof breaking the bracket 54 during the collision of the vehicle.

The hole 62 is provided as follows.

The bracket 54 free from the hole 62 is molded from molten resin throughthe use of a mold 71 (See FIG. 4A to FIG. 4D). Thereafter, machiningoperation is performed on a part including the cold shut portion 61 tothereby provide the hole 62.

The hole 62 may have its various sizes or contours to provide furthersmall strength of the cold shut portion 61. Namely, the further smallstrength of the cold shut portion 61 is achieved by providing the hole62.

For example, the hole 62 is made large in size to thereby reduce thesize or cross-sectional area of the cold shut portion 61. This reductionprovides decreased fracture strength of the bracket 54.

As shown in FIG. 3, the transmission upper mount 34 has a side wall 65of generally pentagonal configuration. The side wall 65 has boltapertures 66 formed to allow the bolts 51 to be inserted therethroughfor attachment of the transmission upper mount 34 to the front sideframe 15.

Discussion will be made as to how the bracket 54 is molded from moltenresin.

As shown in FIG. 4A, molten resin 74 is injected through an injectionport 73 into a cavity 72 of the mold 71, as indicated by arrow A. Themold 71 has a columnar part 76 disposed within the cavity 72. The cavity72 has first and second passageways 75 a, 75 b each formed between aninner surface 71 a of the mold 71 and an outer surface 76 a of thecolumnar part 76. The cavity 72 also has a joining space S cooperatingwith the first and second passageways 75 a, 75 b to surround thecolumnar part 76. Each of the first and second passageways 75 a, 75 bcommunicates with the injection port 73 and the joining space S.

After passing through the injection port 73, the molten resin 74 hits acorner 76 b of the columnar part 76 to divide into two flows or parts ofthe molten resin 74. One part of the molten resin 74 is referred to as“first resin 74 a”. The other is referred to as “second resin 74 b”. Thefirst resin 74 a has its leading end surface 74 a′ while the secondresin 74 b has its leading end surface 74 b′.

As shown in FIG. 4B, the first and second resins 74 a, 74 b flow throughthe first and second passageways 75 a, 75 b, respectively. At this time,one half of the cavity 72 is occupied by the molten resin 74.

As shown in FIG. 4C, the first and second resins 74 a, 74 b flow intothe joining space S. Then, the respective leading end surfaces 74 a′, 74b′ of the first and second resins 74 a, 74 b partly come together orcontact each other.

As shown in FIG. 4D, the cavity 72 is completely filled with the moltenresin 74. The leading end surfaces. 74 a′, 74 b′ come together, or havetheir entire areas meeting each other to provide the cold shut portion61 therebetween. With the leading end surfaces thus held in contact witheach other, the molten resin 74 is hardened to thereby provide the coldshut 61 as indicated by a phantom line.

Discussion will be made as to how the transmission upper mount 34 isbroken in relation to FIG. 5A and FIG. 5B.

With respect to FIG. 5A, for example, when the vehicle accelerates, thetransmission upper mount 34 is subjected to a force F1 through themotive power source 13, as shown by an open arrow. In other words, theforce F1 acts on the transmission upper mount 34 in a direction from afront part of the vehicle body to a rear part of the vehicle body.

Upon undergoing the force F1, the elastic member 56 is deformed todisplace the inner cylindrical member 55 rearwardly of the vehicle body.This makes it possible to withstand or absorb the force F1.

With respect to FIG. 5B, for example, when the vehicle collides withsome object, the transmission upper mount 34 is subjected to a force F2through the motive power source 13, as shown by an open arrow. In otherwords, the force F2 acts on the transmission upper mount 34 in thedirection from the front part of the vehicle body to the rear part ofthe vehicle body.

Upon exertion of the force F2 on the transmission upper mount 34, thecold shut portion 61 and the weak portion 63 of the resinous bracket 54are fractured to thereby displace the motive power source 13 rearwardlyof the vehicle body, absorbing the collision energy or the collision ofthe vehicle with the object.

As described with reference to FIG. 1, FIG. 2 and FIG. 4D, the engine 10and the transmission 11 cooperate with each other to define the motivepower source 13. The motive power source 13 is supported by the rightand left front side frames and the subframe 12. The left one of thefront side frames support the motive power source 13 through thetransmission upper mount 34. The transmission upper mount 34 includesthe inner cylindrical member 55 mounted to one of the motive powersource 13 and the front side frame 15, the resinous bracket 54 mountedto the other, and the elastic member 56 connecting the inner cylindricalmember 55 to the resinous bracket 54. The bracket 54 has the cylindricalportion 57 defining the space 58 of cylindrical configuration. Thecylindrical portion 57 surrounds the inner cylindrical member 55 withthe given interval d provided therebetween. The bracket 54 has the coldshut portion 61 formed when the bracket 54 is molded out of molten resin74 through the use of the mold 71. The bracket 54 has the weak orfragile portion 63 having the arc-shaped hole 62 formed to extendvertically through the cold shut portion 61. The mold 71 has the cavity72 formed therein. The mold 71 has the columnar part 76 positionedwithin the cavity 72 and arranged to provide the cylindrical portion 57during the molding of the bracket 54. More specifically, during themolding of the bracket 54, the columnar part 76 serves to divide themolten resin 74 into the two parts 74 a, 74 b. The parts 74 a, 74 b flowwithin the cavity 72 in such a manner as to surround the columnar part76 and join together to provide the cold shut portion 61 therebetween.

The hole 62 may be changed in size or disposed in different positions tocooperate with the cold shut portion 61 of smaller strength so as tochange the fracture strength of the bracket 54 of the transmission uppermount 34.

The motive power source 13 is subjected to vibration produced when thevehicle is in normal operation, for example, when it accelerates,decelerates, skids, or travels over a bad road. Production of suchvibration exerts a force (normal force) on the transmission upper mount34. The elastic member 56 of the transmission upper mount 34 is thendeformed to absorb the vibration without breaking the resinous bracket54.

During head-on or offset collision of the vehicle with another vehicleand the like, the transmission upper mount 34 is subjected to a force(collision force) through the motive power source 13. The resinousbracket 54 is then broken to absorb the collision.

Thus, the transmission upper mount 34 is designed to perform a properoperation in response to both the normal operation and collision of thevehicle.

The hole 62 need not extend vertically through the cold shut portion 61as explained above. Instead of the hole 62, any cutout, slit, recess orgroove may be formed on the cold shut portion 61 without extendingvertically through the latter.

INDUSTRIAL APPLICABILITY

As discussed above, an engine mount of the present invention includes abracket having a cold shut portion and a fragile portion provided at thecold shut portion. The cold shut portion and the fragile portioncooperate with each other to provide such a small strength that theengine mount is fractured to allow the rearward displacement of anengine during collision of a vehicle with some object to thereby absorbthe collision. The thus arranged engine mount is useful particularly ina technique for absorbing the collision of a vehicle.

1. An engine mount for mounting to a vehicle body a motive power sourceincluding an engine and a transmission, comprising: an inner cylindricalmember to be mounted to one of said motive power source and said vehiclebody; an outer mounting member to be mounted to the other of said motivepower source and said vehicle body, said outer mounting member beingelastically connected to said inner cylindrical member; and said outermounting member having a cylindrical portion loosely receiving saidinner cylindrical member therein such that said inner cylindrical memberis movable in both axial and radial directions thereof relative to saidcylindrical portion, said outer mounting member having a weak portionfor fracturing said outer mounting member to displace said motive powersource rearwardly of said vehicle body during collision of said vehiclebody, said weak portion being provided at a cold shut portion, formedwhen said outer mounting member is molded from molten resin, of saidouter mounting member.
 2. An engine mount according to claim 1, whereinthe molding of said outer mounting member is performed through the useof a mold having a cavity formed therein and a columnar part disposedwithin said cavity to provide said cylindrical portion during themolding of said outer mounting member, said columnar part being capableof dividing said molten resin into two parts during the molding of saidouter mounting member, such that the two parts of said molten resin flowwithin said cavity to surround said columnar part and join together toprovide said cold shut portion.
 3. An engine mount for mounting to avehicle body a motive power source including an engine and atransmission, comprising: an inner cylindrical member to be mounted toone of said motive power source and said vehicle body; a resinous outermounting member to be mounted to the other of said motive power sourceand said vehicle body; an elastic member connecting said innercylindrical member to said outer mounting member; said outer mountingmember having a cylindrical portion surrounding said inner cylindricalmember with a predetermined interval provided therebetween; and saidouter mounting member having a cold shut portion and a weak portionprovided at said cold shut portion, said cold shut portion being formedwhen said outer mounting member is molded from molten resin through theuse of a mold having a cavity formed therein and a columnar partdisposed within said cavity to provide said cylindrical portion duringthe molding of said outer mounting member, said columnar part beingcapable of dividing said molten resin into two parts during the moldingof said outer mounting member, such that the two parts of said moltenresin flow within said cavity to surround said columnar part and jointogether to provide said cold shut portion.